Patent GB-481296-A (GB)
Title: Improvements in or relating to thermostatically operated electric switches
IPC: H01H35/26
Filed: 1936-09-23
Abstract: 481,296. Thermal switches. DIAMOND H SWITCHES. Ltd.. and TURNER, C. A. Sept. 23, 1936, No. 25816. [Class 38 (v)] A thermally-operated switch for use with electric cookers, refrigerators and the like, of the kind comprising a casing, a bellows and contact members operated by the bellows, is provided with a mounting comprising a hollow member enclosing means for moving the bellows longitudinally on rotation of a handle, for the purpose of adjusting the temperature at which the switch operates. In one construction, Fig. 1, the switch is of the kind described in Specification 460,748, and comprises a cup-shaped casing 1 housing the bellows 2, to the front end of which is attached a saucer-shaped member 3 engaging with an adjusting screw 4. The rotation of the screw is prevented by providing it with a flange 6 which engages a retaining plate 5 formed with bifurcated ends 7 engaged by rearward extensions 8 of a locating plate 9, which is formed with forward projecting lugs adapted to enter holes in the rear of the panel on which the switch is mounted. The plate 9 is secured to a tubular bush 10 formed with a screwed portion 11 for receiving a nut by means of which the switch is secured to the panel. Within the bush 10 is mounted a sleeve member 14 adapted to be rotated by means of hooks 15 to which a handle is attached. The sleeve 14 is adapted to drive an inner adjusting sleeve 16 having a screwthreaded engagement with the screw 4, one end of the sleeve 16 being knurled to provide a driving connection with the sleeve 14. For the purpose of regulating the initial position of the bellows with respect to the operating handle, a set screw 17 is provided, which is screwed into the sleeve 16. By slackening and depressing the screw 17 the sleeve 16 can be disconnected from the sleeve 14, rendering the drive hook 15 free to be turned to any desired position. In a modified construction, Fig. 5, the housing 1a of the bellows is provided with a retaining bush 20 having a threaded stem adapted to be passed through a hole in the panel and secured by a nut 21, a locating plate 22 with lugs 24 being provided for engaging recesses in the back of the panel. The position of the bellows is adjusted by a sleeve member 25 mounted in the bush 20, the forward end of the sleeve being formed with an external shoulder 26 which is tapped to receive screws 27. The latter secure in position a ring member 28 formed with a tongue 29 which can move in an annular groove 30 in the boss 20, the arrangement permitting of adjustment of the member 28 with respect to the sleeve 25. The angular setting of these parts is fixed by a clamping disc 31, and a stop 32 is provided to limit the rotational movement of the ring 28 and sleeve 25. The operating handle 35 is attached 'by means of a central screw 36 received within a tapped hole in the disc 31, the outer end of the screw having a cross-bar 37, Fig. 6, formed with lugs 38 and projecting tongues 39 engaging slots 40 in the handle. The driving connection between the handle and the member 28 is provided by a ring member 42 formed with lugs 43, which enter the slots 40 in the handle, and with an inwardly extending lug 45 which engages a slot 44 in the member 28. The ring member 42 is held in position by coiled springs 46, 47. The handle is provided with a translucent portion 49 marked with a scale of temperatures, which scale co-operates with a fixed mark opposite a small hole in the panel. A low power lamp 50 mounted on a holder 51 having a rectangular base 52 and two leaf contacts 53, 54 is arranged between the base of the switch and the inner side of the panel in such a manner that on sliding the lamp holder into position, the leaf contacts engage and lock with contacts 55, 56 extending from the body of the switch. A parabolic reflector may be provided at the rear of the lamp.